Apparatus and method thermal regenerative gas processing

ABSTRACT

An integrated incinerator and heat exchanger unit of modular construction capable in conjunction with other units or alone of efficiently removing pollutents carried by the exhaust gas flow of an industrial system. The unit comprises a boxlike enclosure having a series of internal flues each containing a static, heat exchange, packed bed of particulate material and being in flow communication with the other flues of a unit through a common chamber, the chamber including one or more burners for heating the beds, each unit having a common inlet duct and a common outlet duct with flow control means therein to permit predetermined entry and exit of flow into and out of respective flues, the unit being capable of burning out trapped solids in the heated beds by means of temporary isolation of their respective flues, and the unit including a self-limiting ambient air entry for each flue to purge its bed and improve incineration efficiency.

United States Patent 1 1 3,634,026

[72] Inventors WilliamL.Kuechler 3,067,002 12/1962 Reid 23/2E .lenkintown; 3,109,715 11/1963 Johnsonetal. 23/2E Lyle E. McCoy, Norristown, both of Pa. 3,172,251 3/1965 Johnson 23/2 E [21] Appl. No. 844,995 3,211,534 lO/l 965 Ridgway 23/277 C [22] Filed July 25,1969 3,295,919 1/1967 Henderson et al.... 23/2 E [45] Patented Jan. 1], 1972 3,511,595 /1970 Fuchs 23/2 8 [73] Asslgnee a y & .Schwanz Primary Examiner- Earl C. Thomas 8 elphlapa' Attorney-Roberts. Vermut [54] AB STRACT: An integrated incinerator and heat ei tchanger 12 CI 5 D unit of modular construction capable 1n con unction with rawmg other units or alone of efficiently removing pollutents carried [52] US. Cl 23/2 C, by the exhaust gas flow of an industrial system. The unit com- 23/277 C, 1 /8 A, 263/ prises a boxlike enclosure having a series of internal flues each [51] Int. Cl B0ld 53/34, containing a static, heat exchange, packed bed of particulate F23g 7/06 material and being in flow communication with the other flues Field of Search 23/2.1, 2.2, of a unit through a common chamber, the chamber including 3.1, 4, 277 C, 2 C; 263/15; /8 A one or more burners for heating the beds, each unit having a common inlet duct and a common outlet duct with flow con- [56] References Cited trol means therein to permit predetermined entry and exit of UNITED STATES PATENTS flow into and out of respective flues, the unit being capable of 1,173,297 2/1916 M11161 263/15 x burning out trapped Solids in the heated beds y means oftem- 2,766,031 10/1956 2615/15 porary isolation of their respective flues, and the unit includ- 239 0 8/1959 Houdry et 23/2 5 ing a self-limiting ambient air entry for each flue to purge its 2,946,651 7/1960 Houdry 23/2 s bed and improve incineration efficiency- PATENIEB JAN! 1 #972 31634026 saw 1 [IF 4 o 1' Wu Li m I iii i INVENTORS i WILLIAM L. KUECHLER LYLE E. Mc COY BY fi hts 40m ATTORNEY PATENIEU JAN! 1 I972 v 31634326 SHEEIEUFQ to WWI.

INVENTORS WILLIAM L. KUECHLER LYLE E. McCOY FMS find ATTORNEY PATENIED JAN! 1 1972 SHEET 3 OF 4 H II MINI...

L. KUECHLER E. McCOY ATTORNEY PATENTED JAN! 1 1572 Fl C5. 5

INVENTORS WILLIAM L. KUECHLER LYLE E. McCOY BY films. WI

ATTORNEY APPARATUS AND METHOD THERMAL REGENERATIVE GAS PROCESSING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of fluid purification systems and, more particularly, to the field of air purification through thermal regeneration by oxidation of pollutants in exhaust gas flows of industrial systems.

2. Description of the Prior Art The prior art has developed over an extended period of time in the area of integrated incinerator and heat-exchanger apparatus for application of thermal regeneration to air purification. Certain of the prior art, as represented by US. Pat. Nos. 2,l2l ,733 and 2,898,202, show enclosures comprising a pair of compartments each containing a static, heat exchanger being exposed to periodic flow reversal for maintenance of bed temperature.

However, the prior art has not made adequate provisions for efficient increase of incineration capacity especially with the emphasis today on pollution control. Also, problems relating to efficiency of incineration have arisen with respect to the prior art and, after extended study by applicants, the problems have been defined to be, among others, the lack of proper flow patterns, uncontrollable flow resistance in the heat exchange beds during flow because of trapped solids carried by the inlet flow, and the lack of bed-purging of entrapped gas at flow reversal periods. Thus, the prior art has failed to meet the needs of industry for a system which can have a readily increased capacity as well as provide improved efficiency in incineration.

Applicants have recognized and defined the problems of the prior art and have proposed solutions therefor, as hereinafter described in detail, to provide preferred purification systems.

SUMMARY OF THE INVENTION This invention is directed generally to a continuous flow, bed-purgeable purification system having controllable bed flow resistance, the system including the process associated therewith.

With reference to the preferred embodiment, this invention is directed to a modular, integrated incinerator and heatexchanger unit which in conjunction with other units may accommodate increased demands for pollution control. The individual unit is an enclosure comprising a plurality of internal flues each having a static, heat exchange, packed bed of particulate material at elevated temperatures through which gases carrying pollutants from an exhaust flow of an industrial system are passed with the pollutants thereby oxidized. Inlet and outlet ducts, which can be extended for a plurality of units, are positioned below the beds and communicate with the flues through timed actuator equipped flow control means, the flues communicating with each other internally by a common chamber having one or more burners therein for restoring heat to the beds during operation as flow, by the predetermined opening of certain of the control means in the inlet and outlet ducts, passes by the burners and down through a bed previously cooled by upward flow to the chamber. Any one flue during operation may be isolated by dampers for burning out trapped solids in its bed while flow continues in the remainder of the unit. Also, an ambient air entry for each flue is provided on its inlet side to permit increased incineration efficiency by purging the flue bed of entrapped gases.

It is there an object of the present invention to provide a thermal regenerative fluid purification system which provides improved efficiencies and improved capacity capabilities.

This and other objects, features and advantages of the present invention will become more apparent when viewing the following description in the light of the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan view, cut away in part, showing a system of modular construction having four units;

FIG. 2 is an elevation view of the system of FIG. I and cut away in part in section along line 2-2 of FIG. 1;

FIG. 3 is an end view, cutaway in part, of the system shown in FIG. 1;

FIG. 4 is another embodiment of the present invention; and FIG. 5 is an enlarged view of the termination area of the communication duct as shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawing with reference numerals, in FIG. 1 a system of modular construction having four units generally designated at 1A, 1B, 1C and ID are shown. Each of the units is a boxlike enclosure in shape and is made of a conventional ceramic material or firebrick with access openings'2 to the interior thereof for purposes of servicing, maintenance and repair. Each of the modular units and the construction as a whole may be encased and reinforced, depending on the end use and the construction materials utilized, with structural steel I- or H-beams or angle members as shown at 3 and may be supported above ground by legs In the instance where a plurality of units are juxtaposed toform a modular construction, conventional duct joint means 7 are utilized to permit flow communication between adjacent inlet and outlet ducts. Also, in an arrangement of four modu- Iar units, as shown in FIG. 1, the outlet duct 6 may be common to both pairs of units although individual outlet ducts of a size similar to ducts 5 may be utilized with the flow therethrough joining in a common duct for exhaust through a chimney or stack. Each of the units has a central top burner 8 which may be gas or oil fed or a combination thereof and provides a flame into the common chamber generally designated at 13 above the dividers 9 which define a plurality of parallel flues generally designated at 10, which, in the case of the units of the preferred embodiment, are six in number. The dividers are preferably made of the same material as the enclosure. The plurality of flues results in a multiplicity of flow paths reducing variations in process-system flow rates and static pressures to a level acceptable for application to most modern continuous or steady state processes.

Each of the flues, as seen in FIGS. 1 and 2, has a grill or expanded metal-type flooring II which supports a static, heat exchange bed 12 of particulate material which could be pieces of ceramic, steel, or other material having a sufficiently high melting point, good heat transfer characteristics, and good flow-through characteristics. Each of the flues communicates through the grill or expanded metal flooring 11 with a communication duct or passage means 19 which provides flow communication between the ducts 5 and 6 and respective flues. Thus, each boxlike enclosure has a plurality of flues in common communication with an upper chamber 13, providing flow communication between the flues above the tops of the dividers, and in individual communication with inlet and outlet ducts 5 and 6 through communication ducts I9 extending below the dividers.

The inlet ducts 5 as seen in FIGS. 1, 2, and 3 are connected through a system of ductwork designated generally at 14 with the exhaust gas flow from one of numerous types of industrial systems such as a dryer, oven, kiln, hood, etc. The exhaust gas flow from an industrial system is fed through the ductwork 14 by a push-pull blower system with the exhaust gas flow entering the purification system through primary intake duct 15, the blower chamber 16 and then through secondary intake duct 17 to distribution duct 18 which splits the flow to the inlet ducts 5 of the multiple unit system. After elimination of a substantial percentage of the pollutants therein, the gas flow enters the outlet duct 6 and from there moves through exhaust duct 20, fan discharge chamber 21 and exhaust stack 72.

The details with respect to the flow of the gas from the inlet duct 5 through the beds of particulate material and into the outlet duct 6 will now be discussed.

Each flue has related therewith a communication duct 19 which terminates in the inlet and outlet ducts 5 and 6. Each duct I9 at both its ends in the ducts 5 and 6 has, as best seen in FIGS. 3 and 5, a timed actuator-equipped flow control means such as the closure member 22 which is pivotally connected through arms 23 to a horizontally extending pivot shaft 24 so as to be capable of movement from a horizontal position closing its respective end of the duct 19 to an almost vertical position opening the end. A cam follower 25 comprises an arm extending downwardly toward the enclosure at an angle of approximately 30 to the horizontal, is fixed with respect to its respective closure member 22 and is pivotable on the shaft 24 therewith. Timed actuation occurs as each follower moves in response to a cam 26 fixed on shaft 27 rotated by a motor not shown. Thus, each of the six communication duct ends within each of the ducts 5 and 6 has an arrangement of closure member, cam follower and cam so that predetermined related openings of the communication duct ends may be accomplished. The relationship of openings is determined by the angular relationship of the cams 26 about the axis of shaft 27 so that sequential openings may be accomplished by angularly displacing the earns 26 about the shaft axis at equal angular intervals.

With a central, top gas or oil burner 8, it has been determined that increased incineration efficiency is accomplished by the opening of respective communication duct ends within the inlet and outlet ducts 5 and 6 sequentially in a somewhat sinusoidal manner so that any inflow on the inlet side on entering chamber 13 will pass adjacent the central burner before exiting to the outlet duct.

For purposes of specific illustration of the flow patterns, the closure members 22 have been designated in the cutout portion of FIG. 1 as 22a-l with corresponding designations (25d, 11d, 12d, etc.) for flues, ducts, beds, etc. The exhaust gas flow from an industrial system such as a dryer is initially received within the primary intake duct 15 and then passes through the blower chamber 16 and up through secondary intake duct 17 into the distribution duct 18 which divides the flow to the inlet ducts 5. As the cam shaft 27 rotates, in order of sequence and viewing the cut away portion of FIG. 1, the closure member 22a of communication duct 19a is opened as the cam 26 moves along the follower a raising it and the member 22a to which it is fixedly related so that member 22a is in open position. On the outlet duct side, the sequential opening of the closure members is staggered in relation to members on the inlet duct side so that closure member 22g of the communication duct 19a is in closed position when the member 22a is in open position. This is requisite to operation of the system because otherwise flow would merely pass from the inlet duct to the outlet duct without passing through the heat exchange beds. The sequential operation of the closure members in the outlet duct is such that when the closure member 22a is in open position, the closure member 22] is in open position. Thus, the flow from the inlet duct 5 enters the communication duct 19a at its end opened by member 22a, and, because the other end of communication duct 19a is closed by member 223, moves through the expanded metal flooring 11a of the flue 10a, up through the bed 12a of particulate material at elevated temperatures, and into chamber 13 where it is heated by the oil or gas burner 8. The flow is then forced by the push-pull blower system down the flue 10d, its bed 12d of particulate material and expanded metal flooring I 1d into the communication duct 19d and from there into outlet duct 6. The flow, of course, chooses flue 10d because the closure member 22j, associated only with the flue 10d on the outlet side is in open position with the other closure members on the outlet side being substantially closed. It can, therefore, be seen that the gas flow from the inlet duct moving up flue 10a and down flue 10d must come into contact with the flame of gas or oil burner 8 in chamber 13. This desired relationship between flow and flame is accomplished by the common openings of closure members 22b and 22k, 22c and 221, 22d and 22g, 22a and 22h, and 22f and 22f, with the openings of members on any one side, inlet or outlet, being sequential and with the flow in each instance passing in chamber I3 adjacent the flame of the burner 8 to thus restore heat thereto.

It should be noted here, although explained in more detail hereafter, that the gas flow on the inlet side of the units is at a relatively low temperature and, as it passes upward through a bed of particulate material at elevated temperature toward the chamber 13, experiences a heat-exchange relationship with the bed and is heated by the bed thereby reducing the temperature of the bed through which it is passing. In order to restore the temperature of the bed to the desired elevated level for pollutant auto-ignition or oxidation, the flow that passes downward through the bed going to the outlet duct is heated to elevated temperature in chamber 13 as it passes adjacent the flame of the burner so that reversed heat exchange with the bed through which it is downwardly passing occurs with the bed being returned to the desired elevated temperatures. For example, when closure member 220 is open, the flow at relatively low temperature passes to chamber 13 through the bed 12a at elevated temperatures cooling the bed, but, when the closure member 22g is open and flow passes downwardly from the chamber 13 after being heated by burner 8 through the bed 121: in its movement to the outlet duct, heat is restored to the bed thereby raising the temperatures to the predetermined desired levels.

Incineration efficiency decreases in relation to the amount of entrapped gases remaining in a bed at the time of flow reversal, such gases not being elevated to proper incineration temperature. Thus, it is important to move these gases into chamber 13 for eventual flow to the outlet duct 6 so as to increase incineration efficiency although at the expense of thermal efficiency. In order to accomplish purging" of the beds, each of the communication ducts 19 adjacent its end in the inlet duct 5 has a downwardly extending tube 30 communicating between the interior thereof and the ambient. The tubes 30 extending downwardly terminate with their ends in a plane at an angle to the vertical as shown in FIG. 3 so that, normally, closure cap 31 hinged to the top of the tube 30 at the tube end would, by force of gravity and/or flow-sensing, keep the tube 30 open to ambient air. As stated previously, each communication duct 19 has open ends governed by closure members 22 in both the inlet and outlet ducts 5 and 6, respectively, the opening of the ends being by cam operation. In order to have the exhaust gas flow of an industrial system move through the unit or units 1, both of the ends of any one communication duct 19, as stated previously, may never be open at the same time since such a condition would permit the gas flow to move from the inlet duct to the outlet duct through the communication duct without passing through the beds of particulate material. However, three conditions may exist with respect to the ends of any one communication duct and still permit continuous operation of the system: both ends may be closed by members 22; and either of the ends may be open with the other closed. These three conditions are now explored with respect to a communication duct 19 and its tube 30 on the inlet side.

With the inlet side communication duct end open and the outlet side communication duct end closed, the tube 30 will be open to ambient but, because of a lack of a significant pressure differential, very little ambient air will pass therethrough into the duct I9. With both communication duct ends closed, maximum ambient moves into duct 19 because of the significant negative static pressure therein and in chamber 13. The ambient air movement pushes the gas flow remaining in the bed of particulate material associated with the duct l9 and the gas remaining in duct 19 into chamber 13 thereby purging the bed. With the inlet communication duct end closed and the outlet communication duct end open, the substantial negative pressure within the duct 19 is sufficient to close the mouth of the tube 30 by cap 31 in opposition to the force of gravity thereon. In the latter condition, there is no incoming ambient air so that no interference with the flow patterns and pressure maintenance of the flow patterns in the unit occur, and there is a volumetric savings in the discharge fan flow.

Since temperature and flow conditions have been referred to above in generalities, the following specifics should be construed as exemplary of only one set of operating conditions and need be modified to suit the requirements of incineration of the specific gas flow constituents as well as other variables introduced by a change of inputs. The exhaust gas flow from an industrial dryer might be at a temperature of approximately 230 F. and introduced to the inlet duct 5 at a flow rate of approximately 3,900 c.f.m. after passing through the blower chamber 16. The beds of particulate material are initially heated by the gas or oil burner 8 to achieve an average temperature gradient of approximately 33 F. per inch depth working from a low temperature adjacent the expanded metal flooring to a temperature at approximately l,600 F. adjacent the chamber 13. Once in steady state operation, the burner need only add sufiicient heat (between 6 to 12 million B.t.u.s per hour) to provide for insulation radiation and conduction losses and gross thermal inefficiencies of burning or heat exchange. Thus, the pollutant constituents of the exhaust gas flow from the dryer will be incinerated, i.e., reach their autoignition temperature, at different depth levels of the bed with some incineration occurring in the chamber 13 depending on the constituent oxidation characteristic. Since the inlet flow is at approximately 230 F the bed of particulate material of approximately 3 feet in depth in the flue which receives the inlet gas flow is cooled as the flow passes therethrough to the chamber 13. Since the characteristic bed temperature for the particular exhaust gas flow from the dryer is requisite to proper incineration of the pollutant constituents in the flow, the packed bed must be restored to the proper temperature in order to efficiently perform This is accomplished, as stated previously, by the sequential openings of inlet and outlet closure members 22 so that the flow between the inlet and outlet ducts passes adjacent the oil or gas burner in chamber 13. Under the latter condition, the gas flow in chamber 13 is heated to approximately l,600 F. so that in passing downwardly through a bed previously cooled, heat energy is returned to the bed and the desired temperatures restored. Because of the heat exchange in restoring the bed to elevated temperatures, the outlet air flow may discharge at a temperature between 300 and 500 F.

To prevent outward leakage of unincinerated gases and hotspots in the casing, it is generally preferably to maintain the static pressure in the chamber 13 slightly below ambient and, in order to accomplish this, the capacity of the exhaust blower is controlled, Control for the latter purpose may be accomplished by means ofa pressure sensor within the outlet duct 6, which senses pressure changes therein and signals the pressure condition change to the blower unit. Thus, when the pressure in the outlet duct rises, the capacity of the outlet blower is automatically increased to maintain the slight negative pressure in the chamber 13 and when the pressure in the outlet duct falls, the capacity of the outlet blower is automatically reduced.

After substantial performance of the air purification system, solids carried by the exhaust gas flow from an industrial system may become trapped on the upstream sides of beds adjacent the flooring, thereby increasing resistance to flow and decreasing incineration efficiency due to partial decomposition and entrainment of the existing flow. In order to reduce the flow-resistance to normal, a burn-out phase of the system is initiated. This phase may relate to any one bed of particulate material of any unit or to an entire unit ofa modular construction, and, in each instance, flow continues through the remainder of the system. The burn-out" phase is accomplished by the complete or partial closing off of the inlet and outlet dampers 51 and 53, respectively, of the communicating duct 19, associated with the bed to be bumed-out," as shown in FIG. 3. These dampers may respectively be operated manually by control knobs 50 and 52 but could also be automatically controlled under conventional control principles in response to a time function, bed characteristic or other. With any one duct 19 or all the ducts 19 of a unit of multiple-unit system closed to flow by dampers SI and 53even though the closure members 22 in the inlet and outlet ducts may be open-the packed bed of particulate material is heated to suitably high temperature by the constant reception of heat energy by radiation, convection and conduction from the oil or gas burner without subsequent reduction by movement of cooler inlet flow. As the high temperatures, usually between 800 and l,200 F., are reached throughout the bed depth, the solids trapped in the upstream part of the bed are carbonized or burned-out" into gaseous products. In order to remove the carbonized or burned-out" gaseous constituents, a feedback duct or duct means 54 may be incorporated communicating between respective ducts l9 and the inlet duct 5. The feedback duct 54 has flow manually or automatically controlled under conventional principles by a damper 55 which permits desired flow of the carbonized constituents back through the entire system as they are received in the inlet duct 5. With dampers 51 and 53 closing the duct 19, the damper 55 controls the flow from chamber 13 through the bed being burned-out" so that it is sufficient to carry the carbonized constituents to the inlet duct for recycling. With this burn-out" phase instituted randomly or sequentially with respect to the beds of respective flues of the unit or units, proper flow conditions including bed flow resistance may be maintained.

As shown in dotted lines in FIG. 1, a bypass duct 40 may be incorporated in the system to permit return of the gas flow from the outlet duct 6 to the inlet 5 for recycling through the system. Such bypass duct may be manually and/or automatically controlled by conventional means as, e.g., dampers, in the duct so that at predetermined timed intervals the outlet flow, especially where incineration efficiency is below normal or low flow conditions prevail, may be recycled for improved results.

A second embodiment of the present invention is shown in FIG. 4. This figure shows an inverted modular unit 60 comprising an enclosure wherein the need for a grill or expanded metal flooring to support the packed bed of particulate material is made unnecessary. The inverted unit generally designated at 60 comprises an outer wall 72 preferably made of a ceramic or tirebrick material and has a centrally located portion which supports a burner 65 and defines a chamber generally designated at 64, similar to the chamber 13 shown in the embodiment of FIG. 2. The sidewalls 71 of the portion 70 extend below the top surface of the outer wall 72 and provide dividers 62 which in conjunction with the divider 62a upstanding on the enclosure base form the flues generally designated at 61. The dividers 62 and their adjacent enclosure outer walls 72 form communication ducts 66 and 67 with inlet and outlet ducts, not shown, extending adjacent each other longitudinally of the enclosure along walls 72 above each of the ducts 66 and 67. The beds of particulate material generally designated at 63 are of the same type, i.e., ceramic or other material having the same characteristics as stated previously with respect to the beds 12 shown in the embodiment of FIG. 2, and are supported by the base of the enclosure. Additional benefits of the inverted unit, aside from the lack of need for an expanded metal flooring, are cooler sidewalls, lower construction costs, and the facilitation of access for entry for purposes of inspection, servicing, maintenance and repair of valves, the upstream packing etc., since access ports may be provided along the outer walls 72 of the enclosure adjacent the beds 63. ln following the preferred embodiment, FIG. 4 should be viewed in transverse section with pairs of flues 61 and ducts 66 and 67 segregated longitudinally by transverse dividers 73 to provide parallel flue sets and related communication ducts. Cam actuated or other timed actuator equipped flow control means, and purging and burning-out phases may be adapted to the inverted unit in analogous fashion to the preferred embodiment.

Each unit, pursuant to the construction hereinabove set forth, may very readily be augmented to provide additional capacity under a modular concept. Thus, additional units juxtaposed with proper conventional sealing of adjacent respective inlet and outlet duct ends and with sufficient supporting and reinforcing structural members may be associated with each other to increase capacity. Of course, variables such as flow rates, may need change in accordance with the increased capacity. With the propensity of each unit for addition, the capacity of incineration may be modified at any time to accommodate increases in the capacity of the industrial system and its related exhaust gas flow.

Finally, constructional safety requirements necessitate a minimum continuous flow such as is accomplished by the present invention even when certain of the flues are experiencing a bum-out phase or purging.

Since the preferred embodiment may be modified as shown in the embodiment of H6. 4, and also, for example, by employing a cylindrical enclosure configuration with flues being defined by radially extending dividers, by utilizing a plurality of side oil or gas burners or combinations thereof rather than a single, top and centrally located burner with predetermined adjustment of the sequence of openings of the closure members 22 to provide proper heat energy restoration of the beds, the preferred embodiment should be viewed as illustrative and not in a limiting sense.

What we claim as new is:

1. Apparatus for continuous, thermal regenerative processing of a gas flow comprising an enclosure formed by a plurality of walls and having at least two internal, parallel dividers defining with certain of said plurality of walls at least three laterally spaced flues therein, heat exchange means in said at least three flues, inlet and outlet conduits means, passage means communicating with each of said at least three flues and said inlet and outlet conduit means to provide flow communication between said inlet and outlet conduit means and said at least three flues, said dividers being spaced from one of said plurality of walls and defining with said wall a chamber within said enclosure in common flow communication with said at least three flues, heating means positioned within said chamber, valve means position adjacent the communication of said passage means with said inlet conduit means and said outlet conduit means to govern flow in said passage means, and means connected to said valve means for controlling actuation of said valve means, said flow passing from said inlet conduit means through said passage means and one of said at least three flues into said chamber across said heating means and exiting from said chamber to said outlet conduit means through another flue and passage means.

2. The apparatus set forth in claim 1 wherein a plurality of enclosures are juxtaposed and joined together by structural means, and adjacent ends of the inlet conduit means of respective enclosures are joined in flow communicative relation and the adjacent ends of the outlet conduit means of the enclosures are joined in flow communicative relationship to form common inlet and outlet conduit means.

3. The apparatus set forth in claim 1 wherein said apparatus includes means for intermittently reducing flow into and out of any of said flues, said heating means is adapted to elevate the temperature of said heat exchange means, and said flow reducing means in conjunction with said heating means burn out material trapped in said heat exchange means by heating said heat exchange means in said any flue while reducing flow in said any flue.

4. The apparatus set forth in claim 3 wherein duct means is connected between said any flue and said inlet conduit means, and said duct means includes means for governing flow between said any flue and said inlet conduit means to permit removal of the gaseous products of the burning out of the material trapped in the heat exchange means of said any flue from said heat exchange means.

5. The apparatus set forth in claim 1 wherein each of said passage means has an opening communicating between the interior thereof and ambient. and means for closing said opening to govern the flow of ambient into said passage means through said opening.

6. The apparatus set forth in claim 5 wherein said closing means precludes flow of ambient through said opening only said valve means permits flow between said passage means having said opening and said outlet conduit means.

7. Apparatus for continuous, thermal regenerative processing of gas flow comprising an enclosure having at least three flues therein, heat exchange means in said flues. inlet and outlet conduit means adapted, respectively to transfer flow to be processed and exhaust processed flow, passage means in flow communication with each of said at least three flues and with said inlet and outlet conduit means. a chamber within said enclosure communicating with each of said plurality of flues and containing heating means adapted to elevate the temperature of said heat exchange means, means controlling flow in said passage means, said flow passing from said inlet conduit means through said passage means and one of said at least three flues into said chamber across said heating means and exiting said chamber to said outlet conduit means through another flue and passage means, and said flow controlling means in conjunction with said heating means burning out material trapped in the heat exchange means by heating said heat exchange means while reducing flow therein.

8. The apparatus set forth in claim 7 wherein duct means is connected between each of said passage means and said inlet conduit means, said duct means including means for governing flow between said passage means and said inlet conduit means to permit removal of the gaseous products of the burning out of the material trapped in the heat exchange means from the heat exchange means.

9. Apparatus for continuous, thermal regenerative, processing of gas flow comprising an enclosure having at least three flues therein, heat exchange means in said flues, inlet and outlet conduit means adapted, respectively, to transfer flow to be processed and exhaust processed flow, passage means in flow communication with each of said plurality ,of flues and with said inlet and outlet conduit means, a chamber within said enclosurecommunicating with each of said plurali ty of flues and containing heating means, means for controlling gas flow in said passage means, said passage means having an opening communicating between the interior thereof and ambient means for closing said opening to govern the flow of ambient into said passage means, said flow passing from said inlet conduit means through said passage means and one of said at least three flues into said chamber across said heating means and exiting said chamber to said outlet conduit means through another flue and passage means, and said closing means precluding flow of ambient through said opening only when said gas flow controlling means permits flow between said passage means having said opening and said outlet conduit means.

10. A process for continuous, thermal regenerative, gas purification in apparatus comprising an enclosure having heating means and at least three flues with heat exchange means therein, inlet and outlet conduit means, passage means in flow communication with each of said at least three flues and said inlet and outlet conduit means, and means for controlling flow in said passage means, comprising the steps of reducing the flow only in the passage means communicating with a flue having heat exchange means experiencing increased flow resistance due to trapped material therein carried by the flow, heating the heat exchange means of said flue communicating with said passage means at reduced flow to an elevated temperature, and removing the gaseous products of the burning out of said trapped material from said heat exchange means.

11. The process set forth in claim 10 further comprising the steps of connecting duct means between said passage means and said inlet conduit means, controlling flow in said duct means and permitting return of the gaseous products upon removal from said heat exchange means to said inlet conduit means through said duct means.

12. A process for continuous, thermal regenerative, gas purification in apparatus comprising an enclosure having at least three flues with heat exchange means therein, inlet and outlet said controlling means precludes gas flow between said passage means and said inlet conduit means and said passage means and said outlet conduit means, and closing said passage means to ambient flow only when said controlling means permits gas flow between said passage means and said outlet conduit means. 

2. The apparatus set forth in claim 1 wherein a plurality of enclosures are juxtaposed and joined together by structural means, and adjacent ends of the inlet conduit means of respective enclosures are joined in flow communicative relation and the adjacent ends of the outlet conduit means of the enclosures are joined in flow communicative relationship to form common inlet and outlet conduit means.
 3. The apparatus set forth in claim 1 wherein said apparatus includes means for intermittently reducing flow into and out of any of said flues, said heating means is adapted to elevate the temperature of said heat exchange means, and said flow reducing means in conjunction with said heating means burn out material trapped in said heat exchange means by heating said heat exchange means in said any flue while reducing flow in said any flue.
 4. The apparatus set forth in claim 3 wherein duct means is connected between said any flue and said inlet conduit means, and said duct means includes means for governing flow between said any flue and said inlet conduit means to permit removal of the gaseous products of the burning out of the material trapped in the heat exchange means of said any flue from said heat exchange means.
 5. The apparatus set forth in claim 1 wherein each of said passage means has an opening communicating between the interior thereof and ambient, and means for closing said opening to govern the flow of ambient into said passage means through said opening.
 6. The apparatus set forth in claim 5 wherein said closing means precludes flow of ambient through said opening only said valve means permits flow between said passage means having said opening and Said outlet conduit means.
 7. Apparatus for continuous, thermal regenerative processing of gas flow comprising an enclosure having at least three flues therein, heat exchange means in said flues, inlet and outlet conduit means adapted, respectively to transfer flow to be processed and exhaust processed flow, passage means in flow communication with each of said at least three flues and with said inlet and outlet conduit means, a chamber within said enclosure communicating with each of said plurality of flues and containing heating means adapted to elevate the temperature of said heat exchange means, means controlling flow in said passage means, said flow passing from said inlet conduit means through said passage means and one of said at least three flues into said chamber across said heating means and exiting said chamber to said outlet conduit means through another flue and passage means, and said flow controlling means in conjunction with said heating means burning out material trapped in the heat exchange means by heating said heat exchange means while reducing flow therein.
 8. The apparatus set forth in claim 7 wherein duct means is connected between each of said passage means and said inlet conduit means, said duct means including means for governing flow between said passage means and said inlet conduit means to permit removal of the gaseous products of the burning out of the material trapped in the heat exchange means from the heat exchange means.
 9. Apparatus for continuous, thermal regenerative, processing of gas flow comprising an enclosure having at least three flues therein, heat exchange means in said flues, inlet and outlet conduit means adapted, respectively, to transfer flow to be processed and exhaust processed flow, passage means in flow communication with each of said plurality of flues and with said inlet and outlet conduit means, a chamber within said enclosure communicating with each of said plurality of flues and containing heating means, means for controlling gas flow in said passage means, said passage means having an opening communicating between the interior thereof and ambient means for closing said opening to govern the flow of ambient into said passage means, said flow passing from said inlet conduit means through said passage means and one of said at least three flues into said chamber across said heating means and exiting said chamber to said outlet conduit means through another flue and passage means, and said closing means precluding flow of ambient through said opening only when said gas flow controlling means permits flow between said passage means having said opening and said outlet conduit means.
 10. A process for continuous, thermal regenerative, gas purification in apparatus comprising an enclosure having heating means and at least three flues with heat exchange means therein, inlet and outlet conduit means, passage means in flow communication with each of said at least three flues and said inlet and outlet conduit means, and means for controlling flow in said passage means, comprising the steps of reducing the flow only in the passage means communicating with a flue having heat exchange means experiencing increased flow resistance due to trapped material therein carried by the flow, heating the heat exchange means of said flue communicating with said passage means at reduced flow to an elevated temperature, and removing the gaseous products of the burning out of said trapped material from said heat exchange means.
 11. The process set forth in claim 10 further comprising the steps of connecting duct means between said passage means and said inlet conduit means, controlling flow in said duct means and permitting return of the gaseous products upon removal from said heat exchange means to said inlet conduit means through said duct means.
 12. A process for continuous, thermal regenerative, gas purification in apparatus comprising an enclosure having at least three flues with heat exchange means therein, inlet and outlet Conduit means, passage means in flow communication with each of said at least three flues and said inlet and outlet conduit means, and means for controlling gas flow in said passage means, comprising the steps of normally maintaining the passage means open to ambient flow, purging the passage means and heat exchange means in flow communication with said passage means of entrapped gases with ambient flow into said passage means and said heat exchange means only when said controlling means precludes gas flow between said passage means and said inlet conduit means and said passage means and said outlet conduit means, and closing said passage means to ambient flow only when said controlling means permits gas flow between said passage means and said outlet conduit means. 